Headlight



R. H. HOLMAN AND F. D. SHENK.

HEADLIGHT. APPLICATION FILED SEPT. 20, 1916- I 1,331,813. Patented Feb. 24,1920.

/ RALPH H. HOLMAN, F STONEHA .ori g'i nal application filed December 16, 191 5, Serial No. 67,105.

. roadway, being in effect 1,224,421, issued May 1,1917.

series of prisms,

' the same below the "UNITED STATES PATENT OFFICE.

SETT S, ASSIGNOBS TO THE LEGALITE A CORPORATION OF MASSACHUSETTS.

M, AND FRANCIS D.- SHENK, MEDFORD, MASSACHTI- CORPORATION, 015 BOSTON, MASSACHUSETTS,

HEADLIGHT.

Specification of Letters Patent. 1 Patented Feb, 24, 1920.

Divided and this application filed S eptember 20, 1916. Serial no. 121.296.

of Middlesex, Commonwealth of Massachu setts, and Medford, .county of Middlesex, Commonwealth ,of Massachusetts, have invented certain new and useful Improvements in Headlights',of,w-h1ch the following is a specification.

This invention relates to headlight screens and particularly to the arrangement of adapted allel beam ofa headlight reflector to depress tribute the light satisfactorily along the a lllVlSlOIl or continu'ation of application, filed, Dec. 16, 1915, now Patent No.

plish this object generally by an arrangement of transverse prisms on the. glare screen which forms the front of a headlight, treating; the upper part of the beam with the angles of'which have a progressively increasing depresser function from the vtop toward the center and treating the lower part of the beam with series of prisms having angles v decreasing from the center toward the bottom, so

' that that portion of the upper part of the part of nation of the roadway.

beam lying nearest the center and of the greatest area is more depressed than the small area of the upper edge while the lower the beam is manner. The central prismsare preferably of'a uniform small angularity. in this manner maximum neutralization of the tendency of the lamp to glare and at the sametime secure a very uniform illumi- The construction and operation of our device will specification which trative embodiment is shown in the accompanying drawing, in which Figure 1 is a front elevation oi a prisv matic screen,

glare, level and tO dlS-r- Serial No. 67,105,v

'lVc accomtreated in the reverse.

We securebemore fully described in the follows and an illus- Fig. 2 is a central section through a lamp I equipped with the same, and

I Fig, 3 is a central a screen. I

In theform of our invention herein illustrated, we provide a lamp of the'usual type consisting of a shell 1 and a bulb'2 with a screen 3. glass disk rovided with means for lateral light distribution and having on its rear face a series of transverse horizontal prisms. Beginning at the upper edge of th lamp where the first prism is short, we in ke the succeeding prisms of slightlyincreasingaugula'rity, for example, the first six prisms beginning at the top are respectively of 5, 6, 6%, 7, 7% and 8 degrees. The corresponding six prisms at of the screen are ter downward so that the short prism at the bottom is again a 5 degree prism, the next above it is 6 and so on in reverse order to the top series thus again giving a maximum depressor function to the long prism adjacent the middle portion of the body portion anda series of sive angular function 1. A refractive screen for a comprising a For this purpose 5 or even less- The exact degree of tions of the screen reversed in the progres-.

time give a' distribu-- be approximately uniform lamp to the farthest point vertical section through a 'The screen 3 consists of a circular thelower face decreased from the centransverse prismatic elements inothe upper transverse and, lower portions thereof 'having an op sitely progressiveangular gradation relative to each other, and an intermediate zone of risms o1- uniform angularity.

2. A re active screen for a headlight,

comprising a body portion, and a series of transverse prismatic elements of an angularity increasing from the to toward the center and decreasing from t e center to ward the bottom, and in intermediate zone 10 of transverse'prisms of uniform singularity,

,In testimo y whereof we aflix our signa tures in presence of two witnesses.

. p RALPH H. HOLMAN. c FRANCIS'D. SHENK. Witnesses: 

